Here we issue a bogus error for the first assert in the test. Therein we have
<retval> = (void) (VIEW_CONVERT_EXPR<bool>(yes) || handle_error ());, VIEW_CONVERT_EXPR<int>(value); which has a COMPOUND_EXPR, so we get to cxx_eval_constant_expression <case COMPOUND_EXPR>. The problem here is that we call 7044 /* Check that the LHS is constant and then discard it. */ 7045 cxx_eval_constant_expression (ctx, op0, 7046 true, non_constant_p, overflow_p, 7047 jump_target); where lval is always true, so the PARM_DECL 'yes' is not evaluated into its value. r218832 changed the argument for 'lval' from false to true: (cxx_eval_constant_expression) [COMPOUND_EXPR]: Pass true for lval. but I think we want to pass 'lval' instead. Jakub tells me that's what we do for "(void) expr" as well. [expr.comma] says that the left expression is a discarded-value expression, but [expr.context] doesn't suggest that we should always be passing false for lval as pre-r218832. Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk/11.3? PR c++/105321 gcc/cp/ChangeLog: * constexpr.cc (cxx_eval_constant_expression) <case COMPOUND_EXPR>: Pass lval to cxx_eval_constant_expression. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/constexpr-105321.C: New test. --- gcc/cp/constexpr.cc | 2 +- gcc/testsuite/g++.dg/cpp0x/constexpr-105321.C | 18 ++++++++++++++++++ 2 files changed, 19 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/g++.dg/cpp0x/constexpr-105321.C diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc index e89440e770f..28271d4405d 100644 --- a/gcc/cp/constexpr.cc +++ b/gcc/cp/constexpr.cc @@ -7043,7 +7043,7 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx, tree t, { /* Check that the LHS is constant and then discard it. */ cxx_eval_constant_expression (ctx, op0, - true, non_constant_p, overflow_p, + lval, non_constant_p, overflow_p, jump_target); if (*non_constant_p) return t; diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-105321.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-105321.C new file mode 100644 index 00000000000..adb6830ff22 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-105321.C @@ -0,0 +1,18 @@ +// PR c++/105321 +// { dg-do compile { target c++11 } } + +bool handle_error(); + +constexpr int echo(int value, bool yes = true) noexcept +{ + return (yes || handle_error()), value; +} + +static_assert(echo(10) == 10, ""); + +constexpr int echo2(int value, bool no = false) noexcept +{ + return (!no || handle_error()), value; +} + +static_assert(echo2(10) == 10, ""); base-commit: 5bde80f48bcc594658c788895ad1fd86d0916fc2 -- 2.35.1